Heretofore, thermal sensors have been generally well known in the art. Some of such prior art sensors are of the type which are effective for opening and/or closing related electrical circuits upon sensing a preselected temperature or temperatures. Other of such prior art sensors are of the type which are effective for producing varying electrical signals which are related to or indicative of the magnitude of the sensed temperature.
Further, such prior art sensors may be of the type which in and of themselves provide for electrical grounding or may be of the type which are in series circuit as between a source of electrical potential and an associated electrical load.
In the automotive industry, in particular, the relatively recent trend has been to produce automotive vehicles which are lighter in weight as to thereby reduce the rate of fuel consumption. As a consequence, the entire automotive vehicle as well as the vehicular engine have become physically smaller. The engines, even though smaller, usually have a significantly higher operating R.P.M. and require the monitoring of many operating parameters as well as indicia of engine operation for assuring, among other things, proper fuel metering to the engine, ignition timing and the prevention of engine damage due to, for example, loss of engine oil or oil pressure or excessive engine temperature. In effect, even though the present automotive engines are physically smaller and situated within vehicular engine compartments which provide little space for access to the engine, the various areas or points of monitoring have increased with the result that the number or quantity of sensor assemblies have also increased to the point where it has become difficult to find areas of the engine which can accommodate all of such necessary sensor assemblies.
In some instances a single indicium of engine operation may be employed as a signal for two or more separate and distinct functions. For example, engine operating temperature may be employed for modifying the rate of metered fuel flow (as during cold engine start-up and drive-away) and may be employed for actuation of sensory warning devices so that the vehicle operator is made aware of the engine approaching or attaining an over-temperature condition. As should be apparent, the related electrical circuits leading as to the associated controls and/or warning devices are not compatible with each other. Therefore, in such situations the prior art has usually provided a separate sensor assembly and electrical circuit for each control and/or warning device. This has only aggravated the problem of finding sufficient space on the engine to accommodate all of such required sensor assemblies.
The invention as herein disclosed and described is primarily directed to the solution of the aforestated as well as other related and attendant problems.